Shock-Absorbing Shoes: Bad for Knees?

Those shock-absorbing athletic shoes and clogs designed to protect and cushion the feet may be bad for arthritic knees.

When researchers examined the effects of different types of footwear on people with knee osteoarthritis , they found that going barefoot put less stress on knee joints than wearing foot-stabilizing walking shoes or clogs.

Flip-flops and a flexible walking shoe were also better choices for minimizing impact to the knees during normal walking.

The researchers determined this by assessing a standard measure of knee joint impact, known as knee load.

"Knee loads play an important role in the progression of knee osteoarthritis," researcher Najia Shakoor, MD, of Rush Medical College, says in a news release. "Shoes have traditionally been engineered to provide foot comfort and little previous attention has been directed to the effects that shoes may have on loading of osteoarthritic knees."

She notes that flat, flexible shoes were best for minimizing the impact on knee joints.

The findings were presented at the annual meeting of the American College of Rheumatology in Boston.

Impact of Shoes on Osteoarthritis

According to the Arthritis Foundation, 21 million Americans have osteoarthritis, a chronic disease in which the cartilage that serves as a shock absorber in the joints is broken down over time.

Also known as degenerative joint disease, osteoarthritis is a leading cause of disability among adults. Obesity , age, and joint overuse or injury are risk factors for the condition.

In a 2006 study with a similar design, Shakoor and colleagues reported that going barefoot put less stress on knee joints than wearing everyday walking shoes.

In their latest study, the researchers examined knee loads among 13 women and three men (average age 56 years) with knee osteoarthritis while they were barefoot, and then while they wore a popular brand of clogs, a foot-stabilizing walking shoe, a flat, flexible walking shoe, and flip-flops.

Compared to walking barefoot, the clogs and foot-stabilizing walking shoes were associated with significantly higher knee loading.

"These results highlight the importance of re-evaluating the design of modern day shoes in terms of their effects on knee loads and knee osteoarthritis," the researchers write.

More Study Needed

Rheumatologist Dennis Boulware, MD, says he was surprised by the finding that shoes that are good for ailing feet may not be good for ailing knees.

"This does make me a bit concerned about advising patients about certain types of footwear," he says. "I will certainly pay more attention to knee complaints when I put someone in [foot-stabilizing] shoes for foot problems."

Boulware, who is chief of rheumatology for Kaiser Permanente, Honolulu, adds that larger studies are needed to confirm the findings.

"I am somewhat skeptical because of the small size of the study," he says. "But this is clearly something we need to know more about."

By Salynn Boyles
Reviewed by Louise Chang
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